AU2005237099A1 - Method for thermal recycling household wastes and a device for its realization - Google Patents

Description

Int. Cl. F 23 )0 5/00 Method for thermal recycling household wastes and a device for its realization The interdependent group of inventions relates to recycling techniques for household and industrial wastes containing organic matter as well as for plant trash fr-om agricultural productions.

One of conventional methods of pyrolysis of solid household wastes includes charging wastes for grinding and further transportation of wastes into a reactor for pyrolysis, wherein they are heated by pyrolytic gaseous fuel being burnt in the jacket surrounding the reactor, discharge of wastes in order to extract ferrous metal fractions, adding salts into pyrolytic: gas effluent from the reactor after pyrolysis so as to bind toxic gaseous substances; subsequent gas cleaning from salts, and the supply of purified pyrolytic gas into an incineration chamber, separation of gases effluent from the chamber into two flows, one of these flows is supplied into an exhaust-heat boiler for steam production, and the other flow is directed into a reactor jacket, wherein a certain volume of clean pyrolytic gas after a gas cleaner is subsequently heated in an incineration chamber and supplied into the reactor, wherein the wastes is further interming~ld and agitated by streams of clean pyrolytic gases; and a combustible volume of effluent gas is withdrawn from the reactor jacket, mixed up with fresh air and obtained gas mixture is supplied into an incineration chamber (IJSSS Inventor's Certificate X21l548601, Int. Cl. F 23 G 5/027, Priority date 20.01.88, Bul. of Publication.

X(29, 1990).

A disadvantage of the above-described method consists in the fact that its technological procedure is very cumbersome, moreover, the resulted products require additional neutralizing and recycling, and that partially imposes a considerable stress on the environment.

One of the methods adopted for thermal recycling household wastes in a shaft furnace, which in its technical essence and the results attained (prior art) bears the most close resemblance to the present invention, includes preparation of wastes, charging them into a furnace shaft, heating charged wastes by plasma jets in oxidizing medium, and unloading resulted smelted slag and metal, and withdrawal of effluent gases, with the latter thereafter being cleaned and utilized, and, according to the cited invention, the described process is realized in a pressurized reaction space, and gases are first passed through resulted melt, whereupon they are subjected to a spark discharge, thereafter a certain volume of effluent gases after cleaning is fed back into the reaction space, wherein gas circulation is sustained in the reaction zone, and slag is heated prior to tapping. (Russian Patent 1(21936603, Int. Cl. F 23 G 5100, priority date 24.06-9 1, date of publication Bul. No. 31, 1993).

However, the conventional method, both from the point of view of its feasibility and costs required as well as for some environmental considerations, is neither applicable for recycling, for example, pasty wastes, nor liquid substances, nor for obtaining raw materials suitable for reuse; mnoreover, low efficiency in utilization of available sensible heat of pyrolytic gases can be regarded as one of the disadvantages of the conventional process.

A conventional device for recycling domestic garbage and household wastes contains a housing lined with a heat-resistant material, a tapered feed bin provided with an outlet close to its bottom portion and located adjacent to the housing and having a lid on the top, and inlet pipes for gas and air supply and a gas duct for gas release; wherein the housing throughout its height is divided into a drying zone, a pyrolysis zone and an incineration zone separated one from the others with a pair of flaps mounted at an angle to one another, thereto each flap in the pairs provided at the bin inlet and outlet are made solid and each flap in the pairs separating the zones are provided with perforatjqu~s and the inlet pipes for gas and air supply are located above the pair of flaps at the bin outlet and the gas outlet pipe is located above the pair of flaps at the bin inlet, and the said bin is supplied with an outlet pipe for air release (Patent of Russia 1(2202321 1, Int. Cl. F 23 G3 5100, priority date 18.06.92, date of publication Bul.

No.2 1, 1994).

The process of recycling domestic garbage and household wastes realized in the above described reactor features low output capacity and it is ineffective due to its low controllability and failure to maintain the temperature levels matching the processes occurring simultaneously in the adjacent zones or taking into account composition and particle sizes in initial raw materials.

A conventional device for thermal recycling household wastes, which in its technical essence and the results attained (a prototype) bears the most close resemblance to the present invention, is the one that includes a shaft furnace with a charging device at its top, plasma torches installed round the periphery of the shaft furnace in its overhearth area, a slag notch for slag tapping and a gas duct for effluent gases, and, according to the cited invention, the device is supplied with an under-roof bath adjacent to the over-hearth of the shaft furnace, the said bath has a tap-hole for smelted metal tapping, and pressurized working spaces between the shaft furnace and the bath are separated by means of a vertical partition wall with an opening pmovided in its lower portion and operating as a hydraulic valve, therein a slag notch for slag tapping is constructed as a siphon and is located at the far end of the bath well off the shaft, and an overflow threshold of the said slag notch being well above the level of the opening in the partition wall, and a gas duct is mounted in front of the said slag notch and accommodates an electric discharge device, thereupon the bath is provided with an overflow threshold of the siphon notch and accommodates an electric furnace electrode or a plasniatron, and fuel burners are arranged above the said plasmatron round the periphery of the shaft (Patent of Russia X2l1836603, It. Cl. F 23 G 5/00, Priority date 24.06.9 1, Bul, of publication. Nfi3l, 1993).

A disadvantage of the above described device consists in a low productive capacity of the furnace, which can be attributed to the fact that the above'described process is realized in two stages, i.e. incineration and pyrolysis; moreover, the above described device is not intended for recycling such kinds of wastes as liquid substances, pasty wastes or other materials featuring high visco-elastic properties.

The primary object laid into the basis of the first one in the present group of inventions is to provide an improved method for thermal recycling household wastes, wheftby tdlie to a closed-circuit technological procedure, wastes can be transformed into metal, slag and gaseous constituents, and herewith to ensure efficient utilization of heat and chemnical energy available in effluent gases for other energy-converting devices, to neutralize liquid constituents extracted from wastes, to enhance efficiency of waste recycling, to reduce harmful emissions into the atmosphere, and to increase productivity of the process.

The primary object laid into the basis of the second one in the present group of inventions is to provide an improved device for thermal recycling household wastes, in which, due to modifications introduced into the design of a reactor and also due to rearrangement of units and their interaction in the technological flow to ensure economically advantageous modes of device operation, to enhance a rated capacity of the device, and to minimize pollution of the environment.

The first one of the set objectives is achieved by providing a method for thermal recycling household wastes that includes waste preparation, charging wastes into a shalt furnace, heating them by plasma jets in oxidizing medium, wherein gas circulation takes place in a pressurized reaction space, and subsequent tapping of smelted slag and metal and withdrawal of gases for cleaning and utilization of the latter, and feeding a certain volume of' effluent gases back into a reaction space, and, according to the present invention, a prepared batch of wastes is subjected to volume compression, extracted liquid constituents are neutralized, and the resulting solid product is directedl for predryirig, which is performned by thermal action of gas effluent after utilization; and predried product is periodically charged into the shaft furnace, initially without subjecting the product to thermal action of' plasma jets; and when the furnace is fully charged, the product is subjected to compaction and simultaneous heating it by plasma jets, and thereupon, due to such compaction process an initial heighit of the product column in the furnace reaction space is decreased at a rate proportional to a rate of gasification; and resulting pyrolytic. gas, due to the pressure created by plasmatrons in the shaft furnace, is withdrawn through the top of the furnace, passes through a gascleaning system and is accumulated in a receiver, wheref-rm gas is directed further for utilization of available thermal and chemical energy; hereupon a working medium for plasmatrons represents a mixture of water with cleaned gas resulted from predrying and compressed in a compressor; and the wastes remaining in the shaft furnace are compacted hfuther and melted by plasma jets, whereupon metal and slag are tapped from a shaft fuirnace.

The described process includes four stages: ;7-preparation of wastes, ecological decontamination of liquid constituents in them, and drying; charging predried wastes into a shaft furnace, compression of wastes and simultaneous heating them by plasma jets in oxidizing medium, pyrolysis, and release of pyrolytic gas; circulation of pyrolytic gas in a closed-loop system, which ensures gas cleaning and utilization of available heat, withdrawal of effluent gases with an aim to use them for generation of electric power and steam, extraction and accumulation of water condensate in order to use water and pyrolytic gas for operation of plasmatrons, re-entry of a certain volume of water into a heat exchanger and withdrawal of gas heated therein for drying wastes; smelting metal and slag by subjecting a compacted layer of wastes left in the shaft furnace after pyrolysis to the action of plasmajets.

Due to the accepted sequence of operations realized in the above described process and also due to accurate adjustment of temperature conditions inside the shaft furnace, and also by alteration of intensity and volumes of plasma forming gas in the plasmatrons, the method according to the present invention features such advantages as adequate I'lcxibility of technological procedure, controllability of temperature parameters at individual stages in the process, complete utilization of wastes under set modes of furnace operation as well as completeness of the technological cycle as a whole, therewith preserving the environment clean.

The second of the set objectives is achieved by providing a device for thermal recycling household wastes, comprising a shaft furnace with a charging device, plasmatrons installed at the bottom of the shaft furnace, notches for slag and metal tapping, an additional plasmatron and a pipeline for release of effluent gases, and, according to the present invention, in the top butt end of the shaft furnace there is provided a piston rod with a perforated piston, which accommodates thermocouples and is mounted inside the furnace cavity so that it is capable of limited longitudinal movement along the height of the reaction space of the shaft furnace, herewith the said thermocoupies are electrically connected with a memory block, a drive mechanism for the said piston rod and a mode selector switch, which comes into engagement with a limit stop located in on the piston rod, while the said rod travels inside the shaft furnace; and at the bottom of the shaft furnace there is provided a foreheart with an additional plasmatron, and located above the said tbrehearth, round the outside perimeter of the shaft furnace, there is a gas collector connected with a plasma-chemical gas generator at*c6buA;t&iing plasmastrons, herewith the said charging device commnunicates with a press-filter for waste dehydration and is consecutively connected with a drying unit; a sluice device comprising a receiving reservoir for dried wastes and is supplied with two pilot slide gates, and a screw feeder mounted at the bottom of the said reservoir and communicating with the inside cavity of the shaft furnace through an opening provided in a sidewall of the shaft furnace below the limit of the top most position of rod travel; and a pipeline in the upper portion of the shaft furnace for withdrawal pyrolytic gas, the said pipeline is supplied with a controllable valve and communicates with a cyclonetype gas cleaing device, and further with a desulphurizer and with a receiver, the output of which through a controllable valve and a compressor is connected with a device for utilization of thermal and chemical energy available in pyrolytic gas; a gas release duet of which, through a heat exchanger of a steam generator, is connected with a drying unit; and a contouring gas pipeline for withdrawal of gas from the said drying unit via an air blower is connected with the said plasma-chemical gas generator; and through an additional heat exchanger, a filter and a compressor the said contouring gas pipeline is connected with plasmatrons of a plasma-chemical gas generator, herein during an initial period of warming up the shaft furnace plasmnatrons of the said plasmachemical gas generator are switched on to an outside electric source of energy and to an air compressor; ano the inner cavity of the shaft furnace communicates with a drying unit via an auxiliary pipeline system and a controllable valve; an additional plasmatron mounted inside the said forehearth is connected with a gas cylinder containing liquefied gas, for example, propane, and with an air compressor; and the said drying unit is supplied with an apron conveyer extending along the length of the inner cavity of the drying unit. A device for utilization of thermal energy can be represented by a gas turbine or an internal combustion engine, and a press-filter is supplied with a container for accumulation of iquid constituents and the said container is connected with a tank filled with a neutralizing agent; thereupon the said piston is provided with water cooling.

The said piston in the shaft furnace has perforations for free flow of gas dwing its circulation, and due to provision of thermocouples mounted on the said piston rod and electrically connected with a drive mechanism for the piston rod, a memory block and a mode selector switch, the system ensures maximum controllability over a reverse travel of the piston rod, compression of wastes in the shaft furnace concurrently with their heating, and that results in the minimal total volume of voids occurring in the charged wastes, enhances heat conductivity in wastes and cuts down time required for tqalng.- Provision of a piston rod driven with an independent drive makes it feasible to operate the shaft furnace over a wide range of deformations for wastes compression in the shaft furnace, and in the long run, it ensures a considerable increase in a rated capacity of the shaft furnace in terms of waste volumes being processed, reduces average heat expenditures required for waste recycling, and upgrades the quality and energy content in pyrolytic gas.

A gas collector is intended for forming directional heated gas streams in the pressurized reaction space in the shaft furnace.

With an embodiment of the shaft furnace suggested herein, it is feasible to maintain required temperature parameters in operation by varying an operating parameters and gas consumption in plasmatrons of a plasma-chemical gas generator, and for shaft furnaces having larger heights or diameters the number of plasmachemical gas generators can be decided with due regard to a scale factor.

The system for waste preparation includes a press-filter, wherein wastes are compacted and liquid constituents are separated from solid mass, hereupon liquid constituents are withdrawn and accumulated in a container, wherein they are neutralized, and solid mass is admitted to a drying unit equipped. for example, with an apron conveyer, and through a sluice device solid mass enters the inner cavity of the shaft furnace.

The energy of pyrolytic gas effluent from the furnace is made available by implementation of appropriate devices suitable for utilization of thermal energy, for example, by a combustion engine or a gas turbine with an electric generator. Gas effluent from a device for utilization is supplied into a heat exchanger of a steam generator, wherefrom it flows into a drying unit. A certain volume of gas effluent from the said drying unit, through a gas blower, a filter, an additional beat exchanger and a compressor is supplied to plasinatrons of a plasma-chemical gas generator, and the remaining amount of gas is directly admitted to the plasmna-chemical gas generator.

In case overall dimensions of a shaft furnace are sizable, and, as a result, pyrolytic gas volumes are considerable, additional heat utilization can be realized due to implementation of a steam turbine with an electric generator introduced after a heat exchanger of the said steam generator. Exhaust steam from the steam turbine condenses in a condenser and enters a reservoir for feed water, wherefrom. it is pumped back into the heat exchanger of the steam generator and through a controllable regulator it is sup.jeli4pplasmatrons of a plasma-chemical gas generator.

Thus, the above described device allows for very efficient heat utilization even with a scarce energy content in effluent gas, and it operation doesn't affect the environment.

The described device ensures highly efficient waste recycling with upgraded ecological parameters, including recycling unsorted wastes, and it creates the conditions for a further increase in outputs of recycled wastes according to the growing needs.

Moreover, the energy generated in the device itself can be converted either into heat by plasmatrons or, with the help of other electrical equipment integrated into the technological flow chart, this energy can be converted into mechanical energy.

The method is carried out as follows.

The method of thermal recycling household wastes includes preheating a shaft furnace by plasmatrons of a plasma-chemical gas generator, which during an initial period of warming-up the shaft furnace operate from the outside source of electric energy and an air compressor, without withdrawal of effluent pyrolytic: gases from the said furnace. After the shaft furnace is heated to 150-200 0 C, solid and liquid household wastes are loaded into a charging device of a press-filter, wherein they are subjected to volume compression with concurrent squeezing liquid constituents out of the wastes and collecting them in a separate container for further neutralizing them with a chemical solution. The resulted solid product is directed into a drying unit, wherein a heating agent represents the gases heated up in the reaction space of the shaft furnace and supplied through an additional pipeline system.

When the temperature of the inside wails of the shaft furnace in the area of pyrolysis reaches 300-4001C, pre-dried solid product through a sluice chamber is charged into the shaft furnace without subjecting the product to thermal influence of plasma jets. Then, an auxiliary system that supplies a drying agent is shut off, and pyrolytic gases flow from the shaft furnace through a contouring pipeline. After the furnace is fully charged with pre-dried product, the latter is compacted and simultaneously heated by plasma jets at the controllable temperatures of gases ranging from 300 0 C to 600 0 C at the entrance of the furnace. -While being heated, organic constituents in waste undergo pyrolysis. Owing to pyrolysis and waste compacting, an initial height of a product column in the reactionary space of the shaft furnace decreases at a rate proportional to a rate of gasification.

In the process of heating, pressure and shear deformations act upon solid constituents. When material is subjected to gradual compression, void volume present in material decreases. That gives rise to a calorific value in material, promotes intensive heatrelaseover the whole volume of recycled material, and results in its rapid warming-up.

In the shaft furnace, pyrolytic gas flows from the bottom upwards under a pressure sufficient to overcome a hydraulic resistance of the whole column of charged material and to ensure a pressure which is preassigned by a user of pyrolytic gas at the outlet, therewith a pressure of the gas jets supplied into the shaft furnace by a plasmachemical gas generator is adjusted within the range of 0.05 MPa to 0.1 MPa due to a relatively low moisture content in predried solid products. Owing to pressure created in the reaction space of the shaft: furnace, pyrolytic gas is forced from the furnace top portion and accumulated in a forebearth. The temperature of effluent gas at the furnace outlet is within the range of from 200'C to 500*C. When the forehearth accumulates a sufficient volume of gas, the latter is cleaned with an aim to remove solid particles and sulphur and after that it is utilized, for example, by a combustion engine or a gas turbine to generate electric power. Waste gas after utilization flows into a heat exchanger of a steam generator, and steam is supplied into a steam turbine, which rotates an electric generator. In order to ensure a closed-loop thermodynamic cycle, waste steam from the steam turbine is condensed to water and accumulated in a feed water reservoir, wherefrom it is supplied back- into a beat exchanger of a steami generator. The gas is heated in the beat exchanger to a temperature on the order of about 150 0 C to 200'C3 an is further directed into the ;,one of drying prepared wastes. A certain volume of gas resulting from drying and having a residual temperature ranging from 50 0 C to I 20 0 C is supplied by the gas blower to a pla-chemical gas generator, and the remaining volune of gas is filtered, cooled to a temperature below 30'C and delivered the plasmatrons of a pasma-chemical gas generator. Water from the feed water reservoir is forced at a 4 atm pressure to plasmatrons of a plasma-chemical gas generator and also to an additional plasmatron. Water consumption for a 0.5 MWt plasmatron is within a range of 10 v.1cm.

After each successive full charge of the shaft furnace and thermal decomposition of prepared solid wastes, the process of pyrolysis is completed with resultant accumulation of solid wastes in the forehearth and at the bottom the shaft furnace.

Solid wastes resulted from pyrolysis remain at the furnace bottom, aftd the rest of the furnace space is filled with fresh batches of predried solid product, which is further subjected to compression and heating in the same manner as described above. As wastes are accumulated after pyrolysis, they are subjected to compaction and further heated at a temperature ranging from about I ,500 0 C to 2,000 0 C by a plasma jet of the plasmatron mounted inside. in the said forehearth to produce a complete melt, and wheflutklie resulting fusion is discharged as metal and slag.

Thus, with an aim to ensure an ecoiogicaliy friendly procedure of cleaning effluent gases, household wastes are twice subjected to decomposition at a temperature range, which excludes fonnation and retention of complex chemical compounds.

The energy of resulting pyrolytic gas can be utilized in a number of different ways, as well as combinations of various methods of utilization are also possible. The suggested method makes it feasible to use the electric power from the energy converting devices intended for utilization of energy that is readily generated by the waste recycling system itself, and to power the mechanisms involved in realization of the prewsent method.

A principle arrangement of the device for thenmal recycling household wastes in shown in the accompanying drawing.

The device includes shaft furnace 1 having a metal vertically positioned housing lined with fire-resistant bricks. In the top butt portion of the shaft furnace there is piston 3 mounted on piston rod 2, the said piston protrudes into the inner cavity of the shaft furnace and is capable of preset longitudinal movement while actuated by a drive mechanism 4. The piston has perforations 5 for passing gas flow and is provided with inner channels for a cooling agent (not shown in the drawing). Piston 3 accommodates thermocouples 6 and 7. The device also includes memory block 8 electrically connected to thermocouples 6 and 7, drive mechanism 4 and mode selector switch which comes into engagement with limit stop 10 on piston rod 2 when the latter travels inside the Furnace housing. At the bottom of shaft furnace I is forehearth 11 with additional plasma generator 12. The forehearth is provided with tap notches 13 and 14 for metal and slag discharge. Round the outside perimeter of shaft furnace 1, placed above the forchearth, there is gas collector 15, which communicates via a heat-isolated channel with plasma-chemical gas generator 16 supplied with a set of plasmatrons 17. Pipeline 18 for release of pyrolytic gas is located in the top portion of the shaft furnace and is supplied with flowmeter 19, which via controller 20 is connected with drive mechanism 4. Pipeline 18 through reverse check valve 21 is connected with gas-purification device 22 of a cyclone type, with desuiphurizer 23 for removal of sulphur and its compounds, and with receiver 24. Charging device 25 communicates with press-filter 26, which performs dehydration of wastes and therefrom liquid constituents are withdrawn and collected in container 27. Tank 28 is filled with a chemical used for neutralization of liquid constituents. Connected in succession with press-filter 26, there is a drying unit 29, sluice device 30, which represents a receiving reservoir for dehydmated wastes and a9coqrnwdates two pilot slide gates 31 and 32. In the bottom portion of the reservoir there is screw feeder 33, which communicates with the inner cavity of shaft furnace I through opening 34 provided in a sidewall of the furnace below the top-most limit of travel of piston 3. Apron conveyer 35 is installed along the length of the inner cavity of drying unit 29 Additional plasma generator 12 provided in forehearth 11 is connected with cylinder 36 wit liquefied gas, for example, propane, and with air compressor 37.

The system according to the present invention allows to use any alternative devices suitable for utilization of thermal energy, which can be selected according to the needs of consumers.

As it is shown in the drawing, in one embodiment of the device for the thermal recycling of household wastes, receiver 24 through controllable valve 38 is connected with compressor 39, which communicates with incineration chamber 40 of gas-turbine installation 41 equipped with electric generator 42. An outlet pipeline of the turbine is connected with beat exchanger 43 of a steam generator. Heat exchanger 43 via steam duct is connected with connected with steam turbine 44, which rotates electric generator A pipeline for withdrawal of steamn from steam turbine 44 is connected with condenser 46 and further through condensate pump 47 to reservoir 48 of feed water, wvherefrom, due to operation of feed pump 49 water flows back to heat exchanger 43, and through controllable regulator 50 water is supplied to plasmatrons 17 of plasmachemical gas generator 16 and also to additional plasma generator 12. In addition, heat exchanger 43 via a gas duct is connected to drying unit 29, and a gas-release pipeline envisaged hereto is connected with gas blower 51 and after that it -forks into two branches one branch is connected with plasma-chemical gas generator 16, and the other one through filter 52, additional heat exchanger 53, and compressor 37 is connected with plasmatrons 17 of plasma-chemical gas generator 16 and with additional plasmatron 12. During an initial period of warming up the shalt furnace, plasmatrons 17 of plasma-chemical gas generator 16 are connected with an outside source of electric energy and air compressor 37, and the inner cavity of shaft furnace 1 through auxiliary pipeline 54 is connected with drying unit 29 via controllable valve The device operates as follows: Initial warming up shaft furnace I is performed by low temperature plasma generated by plasma-chemical gas generator 16, wherein during initial warming up the shaft furnace plasmatrones 17 are powered from an outside source of electric energy and are connected to air compressor 37. Check valve 21 in pipeline 18 for release of pyrolytic gas is shut off. Charging device 25 loads household wastes into press-filter 26, wvhe~in. wastes are subjected to compression, thereby liquid constituents are separated from solid mass. Liquid constituents are directed in container 27, wherein a neutralizing agent is concurrently supplied from tank 28. Solid wastes after the press-filter enter drying unit 29, directly on apron conveyer 35. During initial period of warning-up the shalt furnace, hot gas is supplied via auxiliary gas pipeline 54, which connects the inner cavity of shaft furnace I and drying unit 29. Shaft furnace I is heated up until the temperature of its sidewalls reaches the values from 5000(7 to 700 0 C. After initial warming up the shaft furnace, controllable valve 55 shuts off auxiliary pipeline 54, slide gate 31 opens, and conveyer 35 charges dried material into sluice chamber 30. Then plasmatrons, 17 of plasma-chemical gas generator 16 are switched off, slide gate 32 opens, and screw feeder 33 operates and through opening 34 fills the whole volume of the shaft furnace with material. Then slide gate 32 closes and plasmatrons 17 are switched on. Drive mechanism for piston rod 2 is switched on. Piston 3 travels downwards and compacts dehydrated material charged into the inner cavity of the shaft furnace, concurrently, the material is heated by plasma jets at a controllable temperature of gases from ranging from 300 0 C to 600 0 C at the inlet of the furnace. As heating continues, organic constituents in wastes are subjected to pyrolysis and a gas pressure in the shaft furnmace increases. Then check valve 21 operates and pyrolytic gas flows through gas cleaner 22, desulphurizer 23 and enters receiver 24. Values of electric signals from flowmeter 19 indicate a rate of gasification. In pyrolysis, material is subjected to gradual compression by the piston, which travels at a rate proportional to a rate of gasification. While the piston approaches the zone of pyrolysis, the temperature of heating of the piston rod is controlled by thermocouples 6 and 7.

Modes of reverse piston traveling are determined accordingI to a temperature value indicating a degree of heating in the lower portion of the piston, that corresponds to a distance between mode selector switch 9 in different modes of operation of the shaft furnace and the place of location of limit stop 10 on the piston rod that is found experimentally depending on the type of recycled material. Signals from thermocouples 6 and 7 and those from mode selector switch 9 are supplied into memory block 8, and the output of the latter is connected with drive mechanism 4. While the piston is traveling in the shaft furnace, in case when the temperature of the piston reaches 400 0

C

after operation of mode selector switch 9, memory block 8 generates a signal for drive mechanism 4 to return the piston to its initial position and to load a fresh batch of material. If during piston travel its temperature reaches 400 0 C prior to generation of a relevant signal by mode selector switch 9, memory block 8 sends a signal and initiates a moelting. pioces; therewith plasma-chemnical gas generator 16 is switched off and additional plasmatron 12 is switched on, and the piston continues its travel downward until the temperature of heating in its lower portion reached 600 0 C, and with this temperature attained, the piston returns to its initial position, and melting proceeds until the whole amount of wastes resulted from pyrolysis are melted.

After filling the forehearth with pyrolytic gas, the whole system is ready to receive a fresh batch. At this stage, an operator opens controllable valve 38, and gas after cleaning flows through compressor 39 and then is directed for utilization, for example, into a combustion engine or into gas turbine 41. Effluent gas after utilization is withdrawn into heat exchanger 43 of a steam generator, the latter supplies steam for steam-turbine 44, which powers electric generator 45. The steam withdrawn from a turbine is directed into condenser 46, and condensate is accumulated in reservoir 48 for feed water, wherefrom the water is pumped by feed-pump 49 into individual pipelines going to heat exchanger 43, and through controllable regulator 50 to plasmatrons 17 or additional plasma generator 12. Gas flows fromn heat exchanger 43 of the steam generator into drying unit 29. Gas effluent after drying through gas blower 51 is transported via a gas duct into plasma-chemical gas generator 16, and through a main gas line gas is directed through filter 52 into additional heat exchanger 53, wherein gas is cooled to a temperature below 30'C, and through compressor 37, depending on a mode of operation of the shaft fiurnace, gas is supplied either to plasinatrons 17 of the plasma-chemical gas generator or to additional plasma generator 12. Gas prepared in the plasma-chemical gas generator is directed into gas collector 15 and further into the reactionary zone of shaft furnace I The analysis of physical -chemical and electro-therm-al processes occurring in the above described system shows that implementation of the suggested method and device according to the present invention improve qualitatively the mechanism of wastes recycling, promotes efficiency of gas utilization, enhances a factor of utilization of available heat due to generation of electric power directly in the process of waste recycling, and ensures environmental safety of the process due to circulation of a heat carrier in a closed-loop system.

Applicant: Anatoliy Nekiesa Z n'

Claims (9)

1. A method for thermal recycling household wastes, which comprises preparation of wastes, charging themi iiito a shaft furnace and further heating them by plasma. jets in oxidizing medium, wherewith circulation of gases takes place in a pressurized reaction zone, and subsequent tapping smelted slag and metal, withdrawal of gas, subsequent cleaning it for further utilization; and re-entry of a certain volume of effluent gas into the said reaction zone, and, according to the present invention, prepared wastes are subjected to volume compression, and extracted liquid constituents are neutralized, and resulted solid product is directed for predrying, which is performed by thermal action of gas effluent after utilization, and predried product is periodically charged as batches into a shaft furnace, therein during an initial period the said product is not subjected to thermal action of plasma jets, and when the furnace is completely charged, the said product is subjected to compaction and simultaneous beating it by plasma jets, and due to this compaction process an initial height of a product column in the furnace reaction zone is decreased at a rate proportional to a rate of gasification, and resulting pyrolytic gas, due to a pressure created by the plasmatrons in the shaft furnace, is released through the top of the shaft furnace, passes through a gas cleaning system, and accumulate in a receiver, and directed further for utilization of thermal and chemical energy available in said gas; wherein a working medium for the said plasmatrons represents a mixture of clean gas resulted from predrying and compressed in a compressor and mixed with water, and wastes remaining in a shaft furnace are compacted further and smelted by plasma jets, whereupon metal and slag are tapped from a shaft flrnace.

2. A device for thermal recycling household wastes, which includes a shaft furnace with a charging device, plasmatrons provided at the bottom of the said shaft furnace, notches for slag and metal tapping, an additional plasmatron and a gas pipeline for effluent gases withdrawal, and, according to the present invention, in the top butt end of the said shaft furnace there is provided a perforated piston rod, which accommodates thermocouples, the said piston rod is mounted inside the furnace space so that it is capable of limited longitudinal movement along the height of the reaction zone of the said furnace; herein the said thermocouples are electrically connected with a memory block, a drive mechanism for the said piston rod, and a mode selector switch coming into engagement with a limit stop provided on the said piston rod during piston travelling inside a shalt furnace; and at the bottom of a shaft funace there is provided a forehearth with an additional plasmatron. and located above the said forchcartb round the outside perimeter ofra shaft furnace, there is a gas collector connected with a plasma-chemical gas generator accommodating plasmatrons, herewith the said charging device is supplied with a press-filter for waste dehydration and consecutively connected with a drying unit, a sluice device comprising a receiving chamber for dried wastes, which is supplied with two controllable slide gates, and a screw feeder mounted at the bottom of the said receiving chamber and communicating with the inside cavity of a shaft furnace through an opening provided in a sidewall of the said furnace below a top most limit of piston rod travel; and a pipeline for withdrawal pyrolytic gas from the upper portion of the said shaft furnace, the said pipeline is supplied with a check valve and is connected with a cyclone-type gas cleaning unit, with a desuiphurizing device and with a reservoir, an outlet of which through a controllable valve and a compressor is connected with a device for utilization of thermal and chemical energy of pyrolytical gas; and a gas release pipeline, which through a heat exchanger of a steam generator is connected with a drying unit, and a contouring gas pipeline for release of gas effluent from the said drying unit via an air blower is connected with the said plasma-chemical gas generator; and through an additional heat exchanger, a filter and a compressor the said contouring gas pipeline is connected with plasmatrons of a plasma-chemical gas generator.

3. The device of claim 2, wherein, during an initial period of warming-up a shaft furnace, plasmatrons of a plasma-chemical gas generator are powered from an outside electric source of energy and are connected with an air compressor, and the inside cavity of the said furnace communicates with the said drying unit via an auxiliary pipeline system and a controllable valve.

4. The device of claim 2, wherein an additional plasmatron mounted inside the said forehearth is connected with a cylinder containing liquefied gas, for example, propane, and also with an air compressor.

The device of claim 2, wherein the said drying unit is provided with an apron conveyer extending along its length in the inside cavity of the said drying unit.

6. The device of claim 2, wherein a device for utilization of thermal energy represents a gas turbine.

7. The device of claim 2, wherein a device for utilization of thermal energy represents an internal combustion engine.

8. The device of claim 2. wherein a press-filter is supplied with a reservoir for accumulation of liquid constituents and is connected with a vessel for a neutzalizing agent.

9. The device of claim 2, wherein the said pislon rod is water-cooled. Applicant: Anatoiy Nekiesa I Zz. -0"